Your editor is your main point of contact, and you can email them directly.
Feedback is a crucial part of the process. Visual side-by-side comparisons of your editing next to ours is always most helpful.
Also, send any presets you normally use. If you are doing sneak peek galleries for your clients, you can include those in your worksheet. Additionally, you may pre-edit a few photos before sending them in, so we can see exactly what you would typically do to them. If you are doing this, make sure to mention that in the special instructions and to mark the images in Lightroom so your editor can use them accordingly.